Domain Expert Skill
Purpose
Discover, learn, and guide domain knowledge. Helps understand project concepts, terminology, and how to map requests to domain patterns.
Quick Reference
- •Provides: Domain knowledge, concept explanations, request mapping
- •Modes: configure, learn, explain, map
Modes Overview
| Mode | Command | Purpose |
|---|---|---|
| configure | /domain configure | Read domain knowledge from docs |
| learn | /domain learn | Infer domain from code analysis |
| explain | /domain explain <concept> | Answer questions about a concept |
| map | /domain map <request> | Map request to domain concepts |
Configure Mode: /domain configure (Setup)
Discovers domain knowledge from existing documentation.
bash
/domain configure
What it checks:
- •CLAUDE.md (Domain section)
- •README.md (Project overview)
- •docs/domain.md, docs/glossary.md
- •docs/ADR/*.md (Architecture Decision Records)
Output:
code
## Discovered Domain Knowledge **Project:** E-commerce platform **Confidence:** High (domain.md found) ### Glossary (12 terms) | Term | Definition | |------|------------| | Customer | User who has made a purchase | | Order | Customer's request to purchase items | | Cart | Collection of items before checkout | ### Entities (5 found) | Entity | Description | Key Attributes | |--------|-------------|----------------| | Customer | Registered user | id, email, tier | | Order | Purchase request | id, status, items | ### Business Rules (3 found) | Rule | Context | |------|---------| | Orders can only be cancelled within 24h | Order cancellation | **Save this configuration?** [Confirm / Adjust]
Learn Mode: /domain learn
Analyzes domain code to infer entities, relationships, and patterns.
bash
# Analyze all domain code (default) /domain learn --analyze # Learn from specific file /domain learn --from src/domain/order/order.ts
What it analyzes by language:
| Language | Paths Scanned | Patterns |
|---|---|---|
| TypeScript | src/domain/, src/entities/ | class, interface, type, enum |
| Python | domain/, models/ | class, @dataclass, BaseModel |
| Go | internal/domain/, pkg/domain/ | type struct, type interface |
| Rust | src/domain/, src/core/ | struct, enum, trait |
| Java | src/main/java/**/domain/ | class, interface, enum |
Output:
code
## Inferred Domain Knowledge **Method:** Code analysis (23 files) **Confidence:** Medium ### Entities (inferred) | Name | Type | Attributes | Confidence | |------|------|------------|------------| | User | Entity | id, email, status | 95% | | Order | Aggregate | id, items, total | 90% | | Money | Value Object | amount, currency | 85% | ### Relationships
User ──1:N──> Order Order ──1:N──> OrderItem OrderItem ──N:1──> Product
code
### Naming Patterns - Entities: PascalCase nouns (User, Order) - Events: PascalCase past tense (OrderCreated) - Commands: PascalCase imperative (CreateOrder) **Save this configuration?** [Confirm / Adjust]
Explain Mode: /domain explain <concept>
Explains a domain concept with full context.
bash
/domain explain Order /domain explain "value object"
Output:
code
## Domain Concept: Order **Definition:** A customer's request to purchase one or more products. **Type:** Aggregate Root **Attributes:** - id: Unique order identifier - status: pending, confirmed, shipped, delivered, cancelled - items: List of OrderItems - total: Calculated total (Money) **Relationships:** - Belongs to: Customer - Contains: OrderItem (1:N) **Business Rules:** - Cannot be modified after shipping - Can only be cancelled within 24 hours - Total must equal sum of items **Code Location:** src/domain/order/order.ts
Map Mode: /domain map <request>
Maps a user request to domain concepts (used by developer skill).
bash
/domain map "Allow users to cancel orders and get refunds"
Output:
code
## Domain Mapping **Request:** "Allow users to cancel orders and get refunds" ### Entities Involved | Entity | Role | |--------|------| | User | Actor (who cancels) | | Order | Target (what's cancelled) | | Payment | Related (what's refunded) | ### Operations | Operation | Type | Description | |-----------|------|-------------| | CancelOrder | Command | Change order status to cancelled | | RefundPayment | Command | Initiate refund for payment | | OrderCancelled | Event | Emitted after cancellation | ### Business Rules - Can only cancel orders in pending/confirmed status - Refund amount depends on cancellation timing - Must notify customer of cancellation ### Code Locations - Order: src/domain/order/order.ts - Payment: src/domain/payment/payment.ts
DDD Building Blocks
The skill categorizes discovered concepts using DDD patterns:
| Concept | Description | Indicators |
|---|---|---|
| Entity | Object with identity | Has id/uuid field |
| Value Object | Immutable, no identity | readonly, immutable |
| Aggregate | Cluster with root entity | Contains entities |
| Repository | Persistence interface | find, save, delete methods |
| Service | Stateless operations | Service suffix |
| Event | Something that happened | Past tense name |
| Command | Request to change state | Imperative name |
Configuration
Config Location
Config path depends on how the plugin was installed:
| Plugin Scope | Config File | Git |
|---|---|---|
| project | .claude/skills/domain-expert.yaml | Committed (shared) |
| local | .claude/skills/domain-expert.local.yaml | Ignored (personal) |
| user | .claude/skills/domain-expert.local.yaml | Ignored (personal) |
Precedence when reading (first found wins):
- •
.claude/skills/domain-expert.local.yaml - •
.claude/skills/domain-expert.yaml - •Skill defaults
Integration
The domain-expert skill integrates with:
- •developer - Uses
/domain mapto understand requests - •arch - Domain is typically the innermost layer
- •code - Domain code follows specific patterns